Im trying to find a place where I can find 40mm grenades for my grenade launcher. Gun Runners dont seem to have any, and once in a while I happen to find a few at a merchant in a town. but usually I cant find them for sale. Also, I dont see an option to make them at the reloading bench. Any help would be awesome, thank you.

yes a question i'd like answered too.
after i found the initial 30, bought or stolen the supply just dries up completely.

Bump, I want to know as well. the Hoover damn NCR vendor usually has all the ammo stockpiled, but he NEVER has the 40mm, I have checked dozens of times.

Yea Im tring to figure out if the merchants in town have them at random times or if one place will ALWAYS re-stock them or what.

I'd try some of the smaller / weaker vendors, actually. Primm, Novac, the trader down the highway from the NCR California border outpost, etc. (I didn't use a grenade launcher my first playthrough, but I remember seeing small amounts of 40mm ammo everywhere. I wonder if level had anything to do with it.....)

They spawn rarely on all vendors...unless you have high luck I think.

Check the fallout wiki. i think it spawns more at later lvl or something.(unless vendors arent scaled.)

I-88 had like 100 last time i was there. 40 on the arms merchant and 60 on that gun runner mofo

25mm / 40mm / etc are generally found the the various weapons merchants. You should be finding more as you level up and the merchants reset every 3 days.